Stéphanie Jenouvrier, Lise Aubry, Silke van Daalen, Christophe Barbraud, Henri Weimerskirch, Hal Caswell. (2022). When the going gets tough, the tough get going: Effect of extreme climate on an Antarctic seabird's life history (Vol. 25).
Abstract: Individuals differ in many ways. Most produce few offspring; a handful produce many. Some die early; others live to old age. It is tempting to attribute these differences in outcomes to differences in individual traits, and thus in the demographic rates experienced. However, there is more to individual variation than meets the eye of the biologist. Even among individuals sharing identical traits, life history outcomes (life expectancy and lifetime reproduction) will vary due to individual stochasticity, that is to chance. Quantifying the contributions of heterogeneity and chance is essential to understand natural variability. Interindividual differences vary across environmental conditions, hence heterogeneity and stochasticity depend on environmental conditions. We show that favourable conditions increase the contributions of individual stochasticity, and reduce the contributions of heterogeneity, to variance in demographic outcomes in a seabird population. The opposite is true under poor conditions. This result has important consequence for understanding the ecology and evolution of life history strategies.
Keywords: fixed heterogeneity frailty individual quality individual stochasticity SICs unobserved individual heterogeneity
Programme: 109
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Beaulieu Michaël, Dervaux Antoine, Thierry Anne-Mathilde, Lazin David, Le Maho Yvon, Ropert-Coudert Yan, Spée Marion, Raclot Thierry, Ancel André, . (2010). When sea-ice clock is ahead of Adélie penguins clock
. Functional Ecology, 24(1), 93–102.
Abstract: Abstract 1. In Polar Regions, the extent and dynamics of sea-ice are changing. This affects the ocean productivity which consecutively impacts plankton communities and polar top predators like penguins. Yet, the underlying behavioural and physiological mechanisms remain poorly understood. 2.
Keywords: food availability, krill, phytoplankton, seabird, sea-ice retreat,
Programme: 137
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Roux M., Eléaume M., Hemery L.G. & Améziane N. (2013). When morphology meets molecular data in crinoid phylogeny: a challenge.,54: 541-548. . Cahier de Biologie Marine, .
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Roux M., Eleaume M., Hemery L.G. & Ameziane N. (2012). When morphology meets molecular data in crinoid phylogeny: a challenge. 14th International Echinoderm Conference, 12-17 august 2012, Brussels, Belgium..
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Weimerskirch H. & Wilson R.P. (1992). When do wandering albatrosses Diomeda exulans forage? Mar. Ecol. Prog. Ser., 86, 297–300.
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Frédéric Angelier, Olivier Chastel, Adam Z. Lendvai, Charline Parenteau, Henri Weimerskirch, John C. Wingfield. (2020). When do older birds better resist stress? A study of the corticosterone stress response in snow petrels (Vol. 16). Bachelor's thesis, Royal Society, .
Abstract: Life-history theory predicts that, to optimize their fitness, individuals should increase their reproductive effort as their residual reproductive value decreases. Accordingly, several studies have shown that individuals downregulate their glucocorticoid stress response (a proxy of reproductive investment in vertebrates) as they age, and as the subsequent reproductive value decreases. However, and surprisingly, results appear inconsistent, suggesting that the environmental context or the individual state may affect the relationship between age and reproductive effort. Here, we tested for the first time this hypothesis, and more specifically, whether this attenuation of the corticosterone stress response with advancing age depends on the energetic status of individuals. We compared the influence of age on the corticosterone stress response between fasting and non-fasting breeding snow petrels (Pagodroma nivea), an extremely long-lived bird. As expected, we found that the corticosterone stress response was attenuated in old petrels, but only when they were not fasting. Interestingly, this pattern was not apparent in fasting petrels, suggesting that old birds downregulate their corticosterone stress response and increase their parental investment only when they are in good body condition. At the ultimate level, old individuals may maintain a strong corticosterone stress response when fasting because the survival costs of increased stress resistance and parental effort might then outweigh their reproductive benefits.
Programme: 109
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Pardo Deborah, Weimerskirch Henri, Barbraud Christophe, . (2013). When Celibacy Matters: Incorporating Non-Breeders Improves Demographic Parameter Estimates
. PLOS ONE, 8(3), e60389 .
Abstract: In long-lived species only a fraction of a population breeds at a given time. Non-breeders can represent more than half of adult individuals, calling in doubt the relevance of estimating demographic parameters from the sole breeders. Here we demonstrate the importance of considering observable non-breeders to estimate reliable demographic traits: survival, return, breeding, hatching and fledging probabilities. We study the long-lived quasi-biennial breeding wandering albatross (Diomedea exulans). In this species, the breeding cycle lasts almost a year and birds that succeed a given year tend to skip the next breeding occasion while birds that fail tend to breed again the following year. Most non-breeders remain unobservable at sea, but still a substantial number of observable non-breeders (ONB) was identified on breeding sites. Using multi-state capture-mark-recapture analyses, we used several measures to compare the performance of demographic estimates between models incorporating or ignoring ONB: bias (difference in mean), precision (difference is standard deviation) and accuracy (both differences in mean and standard deviation). Our results highlight that ignoring ONB leads to bias and loss of accuracy on breeding probability and survival estimates. These effects are even stronger when studied in an age-dependent framework. Biases on breeding probabilities and survival increased with age leading to overestimation of survival at old age and thus actuarial senescence and underestimation of reproductive senescence. We believe our study sheds new light on the difficulties of estimating demographic parameters in species/taxa where a significant part of the population does not breed every year. Taking into account ONB appeared important to improve demographic parameter estimates, models of population dynamics and evolutionary conclusions regarding senescence within and across taxa.
Programme: 109
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Chauvaud Laurent, Thébault Julien, Clavier Jacques, Lorrain Anne, Strand Øivind, . (2011). Whats Hiding Behind Ontogenetic 13C Variations in Mollusk Shells? New Insights from the Great Scallop (Pecten maximus)
. ESTUARIES AND COASTS, 34(2), 211–220-.
Abstract: Mollusk shells contain geochemical information about environmental conditions that prevailed at the time of formation. We investigated ontogenetic and seasonal variations of δ13C in calcitic shells of Pecten maximus. Ontogenetic variations of δ13Cshell in three large specimens collected in Norway, France, and Spain exhibited a similar linear decrease with increasing shell height. We removed this linear drift (detrending). These three residual time series displayed variations that could be linked to environmental fluctuations. To check it, we reanalyzed the isotopic datasets of Lorrain et al. (Journal of Experimental Marine Biology and Ecology 275:47–61, 2002, Geochimica et Cosmochimica Acta 68:3509–3519, 2004), who worked on three scallops harvested in 2000 in the bay of Brest (France), a well-monitored ecosystem. Lowest values of δ13Cshell detrended were recorded in all shells in late spring–early summer, most likely reflecting corresponding variations in food availability. Our results indicate that ontogenetic and seasonal variations of δ13Cshell cannot be used as a proxy for past δ13CDIC variations but should be considered as promising tools for ecophysiological studies.
Keywords: Scallop shells, Carbon isotopes, Phytoplankton, Ontogeny, Proxy,
Programme: 1090
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Decaulne A., Bhiry N. (2018). What's up on Caribou slope, Wyâshâkimî lake, Nunavik, Canada?.
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Decaulne A., Bhiry N. (2018). What's up on Caribou slope, Wyâshâkimî lake, Nunavik, Canada?.
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